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Trigger RETRY operation where spec says to
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Based on spec at 8ff947d.

Resolves #50.
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@lawrence-forooghian
lawrence-forooghian committed Nov 19, 2024
1 parent b4c57d7 commit 82fed05
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44 changes: 40 additions & 4 deletions Sources/AblyChat/RoomLifecycleManager.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -188,7 +188,8 @@ internal actor DefaultRoomLifecycleManager<Contributor: RoomLifecycleContributor
case detaching(detachOperationID: UUID)
case detached
case detachedDueToRetryOperation(retryOperationID: UUID)
case suspendedAwaitingStartOfRetryOperation(error: ARTErrorInfo)
// `retryOperationTask` is exposed so that tests can wait for the triggered RETRY operation to complete.
case suspendedAwaitingStartOfRetryOperation(retryOperationTask: Task<Void, Never>, error: ARTErrorInfo)
case suspended(retryOperationID: UUID, error: ARTErrorInfo)
case failed(error: ARTErrorInfo)
case releasing(releaseOperationID: UUID)
Expand All @@ -210,7 +211,7 @@ internal actor DefaultRoomLifecycleManager<Contributor: RoomLifecycleContributor
.detaching
case .detached, .detachedDueToRetryOperation:
.detached
case let .suspendedAwaitingStartOfRetryOperation(error):
case let .suspendedAwaitingStartOfRetryOperation(_, error):
.suspended(error: error)
case let .suspended(_, error):
.suspended(error: error)
Expand Down Expand Up @@ -509,7 +510,14 @@ internal actor DefaultRoomLifecycleManager<Contributor: RoomLifecycleContributor

clearTransientDisconnectTimeouts()

changeStatus(to: .suspendedAwaitingStartOfRetryOperation(error: reason))
// My understanding is that, since this task is being created inside an actor’s synchronous code, the two .suspended* statuses will always come in the right order; i.e. first .suspendedAwaitingStartOfRetryOperation and then .suspended.
let retryOperationTask = scheduleAnOperation(
kind: .retry(
triggeringContributor: contributor,
errorForSuspendedStatus: reason
)
)
changeStatus(to: .suspendedAwaitingStartOfRetryOperation(retryOperationTask: retryOperationTask, error: reason))
}
case .attaching:
if !hasOperationInProgress, !contributorAnnotations[contributor].hasTransientDisconnectTimeout {
Expand Down Expand Up @@ -719,6 +727,27 @@ internal actor DefaultRoomLifecycleManager<Contributor: RoomLifecycleContributor
try result.get()
}

/// The kinds of operation that you can schedule using ``scheduleAnOperation(kind:)``.
private enum OperationKind {
/// The RETRY operation.
case retry(triggeringContributor: Contributor, errorForSuspendedStatus: ARTErrorInfo)
}

/// Requests that a room lifecycle operation be performed asynchronously.
private func scheduleAnOperation(kind: OperationKind) -> Task<Void, Never> {
logger.log(message: "Scheduling operation \(kind)", level: .debug)
return Task {
logger.log(message: "Performing scheduled operation \(kind)", level: .debug)
switch kind {
case let .retry(triggeringContributor, errorForSuspendedStatus):
await performRetryOperation(
triggeredByContributor: triggeringContributor,
errorForSuspendedStatus: errorForSuspendedStatus
)
}
}
}

// MARK: - ATTACH operation

internal func performAttachOperation() async throws {
Expand Down Expand Up @@ -781,9 +810,16 @@ internal actor DefaultRoomLifecycleManager<Contributor: RoomLifecycleContributor
case .suspended:
// CHA-RL1h2
let error = ARTErrorInfo(chatError: .attachmentFailed(feature: contributor.feature, underlyingError: contributorAttachError))
changeStatus(to: .suspendedAwaitingStartOfRetryOperation(error: error))

// CHA-RL1h3
// My understanding is that, since this task is being created inside an actor’s synchronous code, the two .suspended* statuses will always come in the right order; i.e. first .suspendedAwaitingStartOfRetryOperation and then .suspended.
let retryOperationTask = scheduleAnOperation(
kind: .retry(
triggeringContributor: contributor,
errorForSuspendedStatus: error
)
)
changeStatus(to: .suspendedAwaitingStartOfRetryOperation(retryOperationTask: retryOperationTask, error: error))
throw error
case .failed:
// CHA-RL1h4
Expand Down
146 changes: 131 additions & 15 deletions Tests/AblyChatTests/DefaultRoomLifecycleManagerTests.swift
View file
Original file line number Diff line number Diff line change
Expand Up @@ -310,23 +310,51 @@ struct DefaultRoomLifecycleManagerTests {

// @spec CHA-RL1h2
// @specOneOf(1/2) CHA-RL1h1 - tests that an error gets thrown when channel attach fails due to entering SUSPENDED (TODO: but I don’t yet fully understand the meaning of CHA-RL1h1; outstanding question https://github.com/ably/specification/pull/200/files#r1765476610)
// @specPartial CHA-RL1h3 - Have tested the failure of the operation and the error that’s thrown. Have not yet implemented the "enter the recovery loop" (TODO: https://github.com/ably-labs/ably-chat-swift/issues/50)
// @spec CHA-RL1h3
@Test
func attach_whenContributorFailsToAttachAndEntersSuspended_transitionsToSuspended() async throws {
func attach_whenContributorFailsToAttachAndEntersSuspended_transitionsToSuspendedAndPerformsRetryOperation() async throws {
// Given: A DefaultRoomLifecycleManager, one of whose contributors’ call to `attach` fails causing it to enter the SUSPENDED status
let contributorAttachError = ARTErrorInfo(domain: "SomeDomain", code: 123)
var nonSuspendedContributorsDetachOperations: [SignallableChannelOperation] = []
let contributors = (1 ... 3).map { i in
if i == 1 {
createContributor(attachBehavior: .completeAndChangeState(.failure(contributorAttachError), newState: .suspended))
return createContributor(
attachBehavior: .fromFunction { callCount in
if callCount == 1 {
.completeAndChangeState(.failure(contributorAttachError), newState: .suspended) // The behaviour described above
} else {
.success // So the CHA-RL5f RETRY attachment cycle succeeds
}
},

// This is so that the RETRY operation’s wait-to-become-ATTACHED succeeds
subscribeToStateBehavior: .addSubscriptionAndEmitStateChange(
.init(
current: .attached,
previous: .detached, // arbitrary
event: .attached,
reason: .createUnknownError() // Not related to this test, just to avoid a crash in CHA-RL4b1 handling of this state change
)
)
)
} else {
createContributor(attachBehavior: .success)
// These contributors will be detached by the RETRY operation; we want to be able to delay their completion (and hence delay the RETRY operation’s transition from SUSPENDED to DETACHED) until we have been able to verify that the room’s status is SUSPENDED
let detachOperation = SignallableChannelOperation()
nonSuspendedContributorsDetachOperations.append(detachOperation)

return createContributor(
attachBehavior: .success, // So the CHA-RL5f RETRY attachment cycle succeeds
detachBehavior: detachOperation.behavior
)
}
}

let manager = await createManager(contributors: contributors)

let statusChangeSubscription = await manager.onRoomStatusChange(bufferingPolicy: .unbounded)
async let maybeSuspendedStatusChange = statusChangeSubscription.suspendedElements().first { _ in true }
let roomStatusChangeSubscription = await manager.onRoomStatusChange(bufferingPolicy: .unbounded)
async let maybeSuspendedRoomStatusChange = roomStatusChangeSubscription.suspendedElements().first { _ in true }

let managerStatusChangeSubscription = await manager.testsOnly_onStatusChange()

// When: `performAttachOperation()` is called on the lifecycle manager
async let roomAttachResult: Void = manager.performAttachOperation()
Expand All @@ -336,7 +364,7 @@ struct DefaultRoomLifecycleManagerTests {
// 1. the room status transitions to SUSPENDED, with the status change’s `error` having the AttachmentFailed code corresponding to the feature of the failed contributor, `cause` equal to the error thrown by the contributor `attach` call
// 2. the manager’s `error` is set to this same error
// 3. the room attach operation fails with this same error
let suspendedStatusChange = try #require(await maybeSuspendedStatusChange)
let suspendedRoomStatusChange = try #require(await maybeSuspendedRoomStatusChange)

#expect(await manager.roomStatus.isSuspended)

Expand All @@ -347,9 +375,41 @@ struct DefaultRoomLifecycleManagerTests {
roomAttachError = error
}

for error in await [suspendedStatusChange.error, manager.roomStatus.error, roomAttachError] {
for error in await [suspendedRoomStatusChange.error, manager.roomStatus.error, roomAttachError] {
#expect(isChatError(error, withCode: .messagesAttachmentFailed, cause: contributorAttachError))
}

// and:
// 4. The manager asynchronously performs a RETRY operation, triggered by the contributor that entered SUSPENDED

// Allow the RETRY operation’s contributor detaches to complete
for detachOperation in nonSuspendedContributorsDetachOperations {
detachOperation.complete(behavior: .success) // So the CHA-RL5a RETRY detachment cycle succeeds
}

// Wait for the RETRY to finish
let retryOperationTask = try #require(await managerStatusChangeSubscription.compactMap { statusChange in
if case let .suspendedAwaitingStartOfRetryOperation(retryOperationTask, _) = statusChange.current {
return retryOperationTask
}
return nil
}
.first { _ in
true
})

await retryOperationTask.value

// We confirm that a RETRY happened by checking for its expected side effects:
#expect(await contributors[0].channel.detachCallCount == 0) // RETRY doesn’t touch this since it’s the one that triggered the RETRY
#expect(await contributors[1].channel.detachCallCount == 1) // From the CHA-RL5a RETRY detachment cycle
#expect(await contributors[2].channel.detachCallCount == 1) // From the CHA-RL5a RETRY detachment cycle

#expect(await contributors[0].channel.attachCallCount == 2) // From the ATTACH operation and the CHA-RL5f RETRY attachment cycle
#expect(await contributors[1].channel.attachCallCount == 1) // From the CHA-RL5f RETRY attachment cycle
#expect(await contributors[2].channel.attachCallCount == 1) // From the CHA-RL5f RETRY attachment cycle

_ = try #require(await roomStatusChangeSubscription.first { $0.current == .attached }) // Room status changes to ATTACHED
}

// @specOneOf(2/2) CHA-RL1h1 - tests that an error gets thrown when channel attach fails due to entering FAILED (TODO: but I don’t yet fully understand the meaning of CHA-RL1h1; outstanding question https://github.com/ably/specification/pull/200/files#r1765476610))
Expand Down Expand Up @@ -1710,16 +1770,38 @@ struct DefaultRoomLifecycleManagerTests {
#expect(await manager.roomStatus == initialManagerStatus.toRoomStatus)
}

// @specPartial CHA-RL4b9 - Haven’t implemented "the room enters the RETRY loop"; TODO do this (https://github.com/ably-labs/ably-chat-swift/issues/51)
// @spec CHA-RL4b9
@Test
func contributorSuspendedEvent_withNoOperationInProgress() async throws {
// Given: A DefaultRoomLifecycleManager with no lifecycle operation in progress
let contributorThatWillEmitStateChange = createContributor()
let contributorThatWillEmitStateChange = createContributor(
attachBehavior: .success, // So the CHA-RL5f RETRY attachment cycle succeeds

// This is so that the RETRY operation’s wait-to-become-ATTACHED succeeds
subscribeToStateBehavior: .addSubscriptionAndEmitStateChange(
.init(
current: .attached,
previous: .detached, // arbitrary
event: .attached,
reason: .createUnknownError() // Not related to this test, just to avoid a crash in CHA-RL4b1 handling of this state change
)
)
)

var nonSuspendedContributorsDetachOperations: [SignallableChannelOperation] = []
let contributors = [
contributorThatWillEmitStateChange,
createContributor(),
createContributor(),
]
] + (1 ... 2).map { _ in
// These contributors will be detached by the RETRY operation; we want to be able to delay their completion (and hence delay the RETRY operation’s transition from SUSPENDED to DETACHED) until we have been able to verify that the room’s status is SUSPENDED
let detachOperation = SignallableChannelOperation()
nonSuspendedContributorsDetachOperations.append(detachOperation)

return createContributor(
attachBehavior: .success, // So the CHA-RL5f RETRY attachment cycle succeeds
detachBehavior: detachOperation.behavior
)
}

let manager = await createManager(
forTestingWhatHappensWhenCurrentlyIn: .initialized, // case arbitrary, just care that no operation is in progress
// Give 2 of the 3 contributors a transient disconnect timeout, so we can test that _all_ such timeouts get cleared (as the spec point specifies), not just those for the SUSPENDED contributor
Expand All @@ -1733,6 +1815,8 @@ struct DefaultRoomLifecycleManagerTests {
let roomStatusSubscription = await manager.onRoomStatusChange(bufferingPolicy: .unbounded)
async let maybeSuspendedRoomStatusChange = roomStatusSubscription.suspendedElements().first { _ in true }

let managerStatusChangeSubscription = await manager.testsOnly_onStatusChange()

// When: A contributor emits a state change to SUSPENDED
let contributorStateChangeReason = ARTErrorInfo(domain: "SomeDomain", code: 123) // arbitrary
let contributorStateChange = ARTChannelStateChange(
Expand All @@ -1748,14 +1832,46 @@ struct DefaultRoomLifecycleManagerTests {
}

// Then:
// - The room transitions to SUSPENDED, and this status change has error equal to the contributor state change’s `reason`
// - All transient disconnect timeouts are cancelled
// 1. The room transitions to SUSPENDED, and this status change has error equal to the contributor state change’s `reason`
// 2. All transient disconnect timeouts are cancelled
let suspendedRoomStatusChange = try #require(await maybeSuspendedRoomStatusChange)
#expect(suspendedRoomStatusChange.error === contributorStateChangeReason)

#expect(await manager.roomStatus == .suspended(error: contributorStateChangeReason))

#expect(await !manager.testsOnly_hasTransientDisconnectTimeoutForAnyContributor)

// and:
// 3. The manager performs a RETRY operation, triggered by the contributor that entered SUSPENDED

// Allow the RETRY operation’s contributor detaches to complete
for detachOperation in nonSuspendedContributorsDetachOperations {
detachOperation.complete(behavior: .success) // So the CHA-RL5a RETRY detachment cycle succeeds
}

// Wait for the RETRY to finish
let retryOperationTask = try #require(await managerStatusChangeSubscription.compactMap { statusChange in
if case let .suspendedAwaitingStartOfRetryOperation(retryOperationTask, _) = statusChange.current {
return retryOperationTask
}
return nil
}
.first { _ in
true
})

await retryOperationTask.value

// We confirm that a RETRY happened by checking for its expected side effects:
#expect(await contributors[0].channel.detachCallCount == 0) // RETRY doesn’t touch this since it’s the one that triggered the RETRY
#expect(await contributors[1].channel.detachCallCount == 1) // From the CHA-RL5a RETRY detachment cycle
#expect(await contributors[2].channel.detachCallCount == 1) // From the CHA-RL5a RETRY detachment cycle

#expect(await contributors[0].channel.attachCallCount == 1) // From the CHA-RL5f RETRY attachment cycle
#expect(await contributors[1].channel.attachCallCount == 1) // From the CHA-RL5f RETRY attachment cycle
#expect(await contributors[2].channel.attachCallCount == 1) // From the CHA-RL5f RETRY attachment cycle

_ = try #require(await roomStatusSubscription.first { $0.current == .attached }) // Room status changes to ATTACHED
}

// MARK: - Waiting to be able to perform presence operations
Expand Down

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